SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'be1eb949b26d5eb7d034b3777db0a958ee3f51421b09453d16f9962266db43c9' 
  AND token = '3oAhKM+YgX70S0fQ35X4vVOPZSEpHMiCLwCLSw28x5Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}